The proposed changes to the law were submitted to parliament Tuesday by the Socialist party and are likely to be approved by other parties, although no date has yet been put forward for a parliamentary debate.

"The idea is to update the law to take better account of dramatic situations and extremely harrowing cases we must find a response to," party leader Thierry Giet said.

The draft legislation calls for "the law to be extended to minors if they are capable of discernment or affected by an incurable illness or suffering that we cannot alleviate."

Belgium was the second country in the world after the Netherlands to legalise euthanasia in 2002 but it applies only to people over the age of 18.

Socialist Senator Philippe Mahoux, who helped draft the proposed changes, said there had been cases of adolescents who "had the capacity to decide" their future.

He said parliamentarians would also consider extended mercy-killing to people suffering from Alzheimer's-type illnesses.

Euthanasia was allowed to an Alzheimer's patient for the first time in the Netherlands last year.

In Belgium, some 1,133 cases - mostly for terminal cancer - were recorded in 2011, about one percent of all deaths in the country, according to official figures.

A seriously ill prisoner serving a long jail sentence this year became the first inmate to die under Belgium's euthanasia laws.